Multiple Warthin Tumors With Epithelial–Myoepithelial Carcinoma of the Ipsilateral Parotid Gland: A Case Report

Case Report

A 68-year-old male presented with a mass in the right parotid region for 10 years. The mass had been gradually enlarging over the previous 3 years and was associated with pain. The patient had a smoking history for approximately 50 years, with 10 cigarettes per day on average.

Physical examination revealed 2 masses in the right preauricular parotid region. One was a firm, 1.5 × 1.0 cm sized mass with poor mobility, and the other below it was soft, 2.0 × 1.0 cm sized and nontender. There were no overlying skin changes or facial nerve palsy. Color doppler ultrasonography disclosed 3 hypoechoic nodules in the right parotid gland (Figure 1A and B).

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Figure 1.

Ultrasound scan of the lower pole of the parotid gland disclosing 2 adjacent hypoechoic nodules, the larger mass measuring 2.0 × 1.0 cm, the other measuring 1.8 × 1.1 cm (A). Ultrasound scan of the preauricular parotid region disclosing a 2.1 × 1.2 × 0.8 cm sized solid hypoechoic nodule (B).

The patient underwent parotid tumor resection. Intraoperatively, 4 homogeneous masses were discovered at the lower pole of the right parotid gland. They were well-circumscribed with the adjacent structures. Another one at the upper pole was firm, with an irregular shape and poorly defined margin (Figure 2A). En bloc removal of the tumors was achieved with the excision of the gland tissue that surrounds the area. Intraoperative frozen pathology of the lesions at the lower pole revealed Warthin tumors (WTs). However, the lesion at the upper pole was found to be malignant. Thus, the surgical incision was expanded, and a right total parotidectomy was performed with all branches of the facial nerve safely separated and preserved (Figure 2B).

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Figure 2.

The surgical specimen showing 2 kinds of tumors, the left 4 are soft and the right is firm (A). All branches of the facial nerve safely separated and preserved (B).

Postoperative pathological examination of the lesions at the lower pole of the right parotid gland showed cystic tumors with intracystic papillary structures (Figure 3A). These were diagnosed as WTs. Pathological examination of the tumor at the upper pole of the right parotid gland showed typical bilayered duct–like structures composed of interlayer epithelial cells and out-layer cells with clear cytoplasm, and hyaline degeneration was seen in the stroma (Figure 3B). Immunohistochemically, CK5/6, CK7, SMA, S-100, P63, Calponin, Vimentin, and β-catenin expressed positively in the tumor tissue (Supplementary material 1-10). This tumor was diagnosed as epithelial–myoepithelial carcinoma (EMC). After a month of recovery, the wound healed well with no redness, swelling, or metastasis. The patient was advised to quit smoking and receive adjuvant radiotherapy or chemotherapy to reduce the high risk of locoregional recurrence.

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Figure 3.

Warthin tumors (WTs; A) with epithelial papillary infoldings surrounded by lymphoid stroma (hemotoxylin and eosin [H&E] stain, original magnification ×10). Epithelial–myoepithelial carcinoma (EMC; B) with bilayered duct–like structures composed of interlayer epithelial cells and out-layer cells with clear cytoplasm (H&E stain, original magnification ×10).

Conclusion

Due to the improvement of tumor diagnosis and treatment, the incidence of multiple primary tumors (MPTs) has increased from 1.7% to 3.4% of all parotid tumors. ¹ Warthin tumor is the most common multifocal tumor, whether unilateral or bilateral, followed by the pleomorphic adenoma. ² To the best of our knowledge, a few cases regarding the coexistence of benign and malignant tumors have been reported in the existing literature, but the combination of EMC and multiple WTs has not been reported until now.

Epithelial–myoepithelial carcinoma accounting for less than 1% of salivary gland tumors is a rare low malignant neoplasm. ³ However, EMC has a high risk of recurrence and blood metastasis. A total parotidectomy combined with postoperative chemotherapy might be beneficial to prevent blood metastasis.

Multiple primary tumors of the parotid gland are characterized by multifocality and multicentricity, which easily lead to misdiagnosis and postoperative recurrence. Accordingly, when the physical examination reveals multiple focal tumors in the ipsilateral gland, especially with pain and facial nerve symptoms, we should be fully alert to carry out detailed auxiliary examinations.

Surgery still represents the first-line treatment in the MPTs therapies. All lesions should be sampled for intraoperative pathological analysis, and further treatment plan should be adjusted in time to improve the prognosis of patients. Pathologists and surgeons should consider the possibility of MPTs to avoid secondary surgery.

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